New study shows how sleep quality Is linked to locus coeruleus activity

Researchers at the University of Liège’s Institute are employing advanced 7 Tesla MRI technology to gain deeper insights into the regulation of sleep.

For a long time, we’ve understood that sleep benefits the brain, and we’ve recognized light’s influence on mood beyond its role in vision. Yet, the intricate workings of these processes in our brains remain a mystery.

A scientific team from the ULiège Cyclotron Research Centre/In Vivo Imaging (GIGA-CRC-IVI) has recently unveiled a crucial connection between the quality of REM sleep (the dream-rich phase of sleep) and the activity of the locus coeruleus. This tiny brain nucleus, resembling a 2cm-long spaghetti strand, resides at the brainstem’s base.

The locus coeruleus, named for its blue appearance during autopsies, projects throughout the brain and spinal cord, releasing the neuromodulator noradrenaline. Noradrenaline serves not only to activate neurons and maintain wakefulness but also influences various cognitive functions, including memory, emotions, stress, and anxiety. Its activity decreases to initiate sleep and ceases during REM sleep, allowing this phase to work independently of noradrenaline. This process helps consolidate or prune synapses during sleep, preparing us for a new day of experiences, according to Gilles Vandewalle, co-director of the GIGA CRC-IVI.

While animal research has confirmed the locus coeruleus’s importance in sleep-wake cycles, verifying its role in humans has been challenging due to its small size and deep location. Ekaterina Koshmanova, a researcher in the laboratory and lead author of an article in JCI Insight, credits the higher resolution of 7 Tesla MRI for enabling the observation of the nucleus during a cognitive task in wakefulness. Their findings suggest that the more active the locus coeruleus during the day, the lower the perceived sleep quality and REM sleep intensity.

Interestingly, this effect appears more pronounced as individuals age, with the impact becoming evident between ages 50 and 70 but not among younger adults aged 18 to 30. These initial findings may shed light on age-related insomnia. They also lay the groundwork for future investigations into the nucleus’s activity during sleep and its potential role in insomnia and the link between sleep and Alzheimer’s disease.

Source: University de Liege

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